Mystery of terrible hound with no end? (8)
I believe the answer is:
whodunit
'mystery' is the definition.
('whodunit' can be a synonym of 'mystery')
'terrible hound with no end?' is the wordplay.
'terrible' indicates an anagram.
'no end?' means to remove the last letter (I've seen 'no end' mean this).
'hound'+'with'='houndwith'
'houndwith' with its last letter removed is 'houndwit'.
'houndwit' is an anagram of 'WHODUNIT'.
'of' is the link.
(Other definitions for whodunit that I've seen before include "detective novel" , "Murderer revealed at the end, US style" , "Crime mystery novel, play or film" , "Crime story (colloq.)" , "Informally, a detective story or play" .)